The Fort Pierre National Grassland is home to a series of spiders previously unknown. A new species, Theridion pierre (Levi & Patrick 2013) is part of the cobweb family of spiders, Theridiidae, the fifth largest family of spiders which boasts 2387 currently recognized species (Platnick 2014). This 1 millimeter spider – about the size of a lead pencil point – is relatively abundant and easily caught on the grasslands. (Photo courtesy of Patrick Brian)

When a new species is discovered on the planet, people usually imagine a discovery process that is dangerous and remote in location. However, one scientist didn’t have to venture far from home to learn about a few new discoveries that has the science community spinning about a native grassland ecosystem in South Dakota.

Two summers ago, Patrick discovered Theridion pierre, a tiny yellowish spider approximately one millimeter long. Recently he also unveiled two other dwarf spiders from genera Ceraticelus and Mermessus. Patrick hopes to have them named after his wife, Traci, and their daughter, Thea.

What exactly does it take to catch a tiny spider amidst and below the long grasses of the Fort Pierre National Grassland?

On four different fields in the Fort Pierre National Grassland, Patrick and his crew used four trapping methods to collect unsuspecting invertebrates: pitfall traps which are cups placed into holes in the ground for bugs to fall into; ramp traps which are Ziploc containers in the ground with ramps leading into them; net-sweeping of vegetation; and sifting through dead grass and organic matter. Theridion pierre was frequently caught in these traps, while the other two species Patrick hopes to name were a little more scarce.

Once captured, the tricky part begins – identifying these small spiders by their eyes, leg spines, and even genitalia, all key identifiers that distinguish one species from another.

“I am not surprised that I am finding new species living in the Fort Pierre National Grassland,” said Patrick. “This particular type of northern mixed-grass prairie hasn’t been heavily sampled, and the protection and management of the land by the USDA Forest Service has helped maintain the integrity of this biologically unique ecosystem.”

Next summer, Patrick will continue his research on the grasslands. Aside from the Theridion pierre, Ceraticelus and Mermessus species, he believes he’s found an additional spider species during his studies. After the grasslands, he plans to head to northeast South Dakota to look for more spiders hiding out in the wetlands, prairie and tree belts.

Some say that anyone can love the forest, but it takes soul to love the grasslands, and who wouldn’t with vistas like these? The Fort Pierre National Grassland teems with rich biodiversity and is home to the new spider species, Theridion pierre. Fort Pierre National Grassland is a mixed-grass prairie that usually receives the most rainfall per year of any grassland, which can be as much 18 inches. (U.S. Forest Service photo)